feat(transitioner): add transitioner to easen the process of protocol…

… changes

Resolves #403

lib/transitions/1.js

@@ -0,0 +1,34 @@
+
+/**
+  * Our first transition is actually the removal of globals and
+  * introducing the setup routine.
+  * Thus the body of this transition is just an empty function, but displays
+  * as all transitions an explanation to the user.
+  */
+module.exports = {
+
+  transition: function() {
+
+  },
+
+  message: function() {
+
+    console.log('Congratulations!\n\n' +
+      'You just migrated from protocol 0 to 1!\n' +
+      'What does that mean for you?\n' +
+      'Quite simple, from 0 to 1 we introduced the setup function and we' +
+      'deprecated some globals, like async or dbm. What this transition does is' +
+      ' grabbing your migrations, replacing the async and dbm definitions and ' +
+      'inserting the setup body if not present.\n' +
+      'It might be possible, that you still run into errors, for example if ' +
+      'you already have had a setup body, it wont be replaced and you might ' +
+      'be missing the default routine of the setup, which provides for example ' +
+      'the dataTypes to your migration.\n\n' +
+      'What do I need to do now?\n' +
+      'Try to rexecute all of your migrations and watch if you run into any ' +
+      'Errors, if you encounter any, you need to manually fix those ' +
+      'problems. But don\'t worry, this protocol transitions happen very ' +
+      'rarely!\n'
+    );
+  }
+};

lib/transitions/transitioner.js

@@ -4,58 +4,66 @@ var updateVersion = require('./update-version.js');
 var ask = require('./ask.js');
 var log = require('db-migrate-shared').log;
 
-var internals = {
-  migrationProtcol: 1,
-  cwd: process.cwd()
-};
+module.exports = function(internals) {
+
+  ask(
+    {
+      properties: {
+        safe: {
+          description: 'This process is going to alter your migrations. We ' +
+          'highly recommend you to backup your migrations or even better safe ' +
+          'the current state with git versioning.\nPlease make sure you don\'t ' +
+          'blow up yourself.\n\nDo you want to continue? [y/n]',
+          message: 'Invalid answer! Do you want to continue? [y/n]',
+          type: 'string',
+          default: 'n',
+          conform: function(value) {
 
-ask(
-  {
-    properties: {
-      safe: {
-        description: 'This process is going to alter your migrations. We ' +
-        'highly recommend you to backup your migrations or even better safe ' +
-        'the current state with git versioning.\nPlease make sure you don\'t ' +
-        'blow up yourself.\n\nDo you want to continue? [y/n]',
-        message: 'Invalid answer! Do you want to continue? [y/n]',
-        type: 'string',
-        default: 'n',
-        conform: function(value) {
-
-          return value === 'y' || value === 'n';
+            return value === 'y' || value === 'n';
+          }
         }
       }
-    }
-  }, function(err) {
+    }, function(err) {
 
-  if(err)
-    return;
+    if(err)
+      return;
 
-  Migration.loadFromFilesystem('migrations/', internals,
+    Migration.loadFromFilesystem('migrations/', internals,
     function(err, migrations) {
 
-    migrations.forEach(function(migration) {
+      var messages = [];
+
+      migrations.forEach(function(migration) {
 
-      var required = tryRequire(migration, internals);
-      var version = (required._meta && required._meta.version) ?
-      required._meta.version
-      : 0;
+        var required = tryRequire(migration, internals);
+        var version = (required._meta && required._meta.version) ?
+        required._meta.version
+        : 0;
 
-      if(version !== internals.migrationProtcol) {
+        if(version !== internals.migrationProtocol) {
 
-        var i;
+          var i;
 
-        for(i = 0; i < internals.migrationProtocol; ++i) {
+          for(i = 0; i < internals.migrationProtocol; ++i) {
 
-          var transition = require('./' + i + 1);
-          updateVersion(required, migration, internals, i + 1);
+            var transition = require('./' + (i + 1));
+            transition.transition();
+            messages[i + 1] = transition.message;
+
+            updateVersion(required, migration, internals, i + 1);
+            log.info('Transitioned ' + migration.name + '.');
+          }
         }
-      }
-      else {
+        else {
 
-        log.info(migration.name, 'was already transitioned to version ' +
-        internals.migrationProtcol + '.');
-      }
+          log.verbose(migration.name, 'was already transitioned to version ' +
+          internals.migrationProtocol + '.');
+        }
+      });
+
+      messages.forEach(function(message) {
+        message();
+      });
     });
   });
-});
+};

lib/transitions/try-require.js

@@ -1,23 +1,49 @@
 var log = require('db-migrate-shared').log;
 var fs = require('fs');
+var cp = require('child_process');
 
 var handled = false;
+var installed = false;
 var removedGlobals = {
   'dbm is not defined': globalHandler,
-  'async is not defined': globalHandler
+  'async is not defined': globalHandler,
+  'Cannot find module \'async\'': installAsync
 };
 
+function installAsync(migration, retry) {
+
+  var cmd = [ 'install', '--save', 'async' ];
+
+  if(installed)
+    retry();
+  else
+    installed = true;
+
+  log.info('Installing async...');
+  cp.spawnSync('npm', cmd, {
+    cwd: migration.internals.cwd,
+    stdio: 'inherit'
+  });
+
+  return retry();
+}
+
 function globalHandler(migration, retry) {
 
   var data = fs.readFileSync(migration, 'utf8');
   data = data.replace(
     /^dbm = dbm \|\| require\(\s+'db-migrate'\s+\)/m,
     'var dbm'
   );
-  data = data.replace(
-    /^async = async \|\| require\(\s+'async'\s+\)/m,
-    'var async = require( \'async\' )'
-  );
+
+  if(data.indexOf('async = async || require') !== -1) {
+
+    handled = true;
+    data = data.replace(
+      /^async = async \|\| require\(\s+'async'\s+\)/m,
+      'var async = require( \'async\' )'
+    );
+  }
   data = data.replace(
     /^var type = dbm.dataType/m,
     'var type'
@@ -38,20 +64,20 @@ function tryRequire(migration) {
 
   try {
 
-    if(handled) {
+    if(handled && !installed) {
 
-      //require(migration.internals.cwd + 'package.json')
-      //cp npm install --save async
+      return installAsync(
+        migration,
+        tryRequire.bind(this, migration)
+      );
     }
 
     return require(migration.internals.cwd + '/' + migration.path);
   }
   catch(ex) {
     if(ex instanceof ReferenceError) {
-
       if(removedGlobals[ex.message]) {
 
-        handled = true;
         log.info(ex.message, 'Initiating removal of old globals...');
         return removedGlobals[ex.message](
           migration.path,
@@ -70,6 +96,13 @@ function tryRequire(migration) {
           'fix the issues and rerun the transitioner again.');
       }
     }
+    else if(removedGlobals[ex.message]) {
+
+      return removedGlobals[ex.message](
+        migration,
+        tryRequire.bind(this, migration)
+      );
+    }
     else {
 
       log.error(ex.stack, migration);